1. Technical Field
The present invention relates to a detection device, a sensor, an electronic apparatus, a moving object and the like.
2. Related Art
A gyro sensor for detecting a physical quantity that changes due to external factors is assembled in an electronic apparatus such as a digital camera or a smart phone, or a moving object such as a vehicle or an airplane. The gyro sensor detects a physical quantity such as an angular velocity, and is used for image stabilization, posture control, GPS autonomous navigation or the like.
For example, a vibration gyro sensor such as a quartz crystal piezoelectric vibration gyro sensor is known as one of the gyro sensors. In the vibration gyro sensor, a physical quantity corresponding to a Coriolis force generated by rotation is detected.
In such a vibration gyro sensor, an unnecessary signal of a detuning frequency due to mechanical vibration such as a disturbance is generated. As a related art technique for removing the unnecessary signal of the detuning frequency, for example, techniques disclosed in JP-A-2007-327943, JP-A-2008-256668, and JP-A-2007-18706 are known.
JP-A-2007-327943 discloses a technique for attenuating a component of a detuning frequency by a low pass filter of a switched capacitor filter (SCF) provided at a subsequent stage of a synchronization detection circuit to remove an unnecessary signal of the detuning frequency.
JP-A-2008-256668 discloses a technique for inputting a signal subjected to synchronization detection to a noise removal unit configured by serially connecting a Butterworth filter and a Chebyshev filter, to thereby remove an unnecessary signal of a detuning frequency.
JP-A-2007-18706 discloses a technique for generating a detuning frequency signal of the same frequency as that of an unnecessary signal of a detuning frequency and subtracting a signal obtained by gain-adjusting the detuning frequency signal from the original signal, to thereby remove the unnecessary signal of the detuning frequency.
However, if a low pass filter with a low cutoff frequency is used in order to remove the unnecessary signal of the detuning frequency, a signal band becomes narrow. Further, in order to attenuate the component of the detuning frequency by increasing the cutoff frequency to secure the signal band, a high-order filter is necessary, which causes a large amount of signal delay in the signal band. In addition, in a method for generating the detuning frequency signal of the same frequency as that of the unnecessary signal of the detuning frequency and then subtracting the signal from the original signal, a circuit becomes complicated, and a circuit size becomes large, which increases the cost.